476
FXUS02 KWBC 261836
PMDEPD
EXTENDED FORECAST DISCUSSION
NWS WEATHER PREDICTION CENTER COLLEGE PARK MD
236 PM EDT SUN APR 26 2026
VALID 12Z WED APR 29 2026 - 12Z SUN MAY 03 2026
...LATE WEEK/WEEKEND SOUTH-CENTRAL TO SOUTHERN U.S. HEAVY
RAINFALL/FLOODING THREAT AND NEW ENGLAND COASTAL LOW GENESIS...
..OVERVIEW
AN INCREASINGLY AMPLIFIED UPPER FLOW PATTERN WILL LEAD TO EPISODES
OF ACTIVE WEATHER ACROSS PARTS OF THE LOWER 48 FOR THE LATTER HALF
OF THE UPCOMING WEEK INTO NEXT WEEKEND. A DEEPENED LOW/FRONTAL
SYSTEM WILL BRING MUCH NEEDED RAIN TO THE EAST MID-LATE WEEK, WITH
WINDY COASTAL LOW DEVELOPMENT LEADING TO MULTI-DAY RAINS INTO
NORTHERN NEW ENGLAND INTO NEXT WEEKEND. THE EJECTION OF A PACIFIC
TO SOUTHWEST U.S. SYSTEM WILL SET THE STAGE FOR HEAVY RAIN FROM
THE SOUTH-CENTRAL TO SOUTHERN U.S. LATE WEEK INTO NEXT WEEKEND.
..GUIDANCE/PREDICTABILITY ASSESSMENT
LATEST GUIDANCE STILL HAS A RELATIVELY GOOD HANDLE ON THE MID-
LARGER SCALE EVOLUTION THROUGH THE MEDIUM RANGE PERIOD DESPITE
INCREASING MID-LEVEL AMPLIFICATION/BLOCKY PATTERN DEVELOPMENT LATE
WEEK/NEXT WEEKEND. AS A RESULT, THE WPC PRODUCT SUITE WAS MAINLY
DERIVED FROM BEST CLUSTERED GUIDANCE OF THE GFS/ECMWF/UKMET AND
GEFS/ECMWF ENSEMBLE MEANS. THIS SOLUTIONS RETAINS GOOD PRODUCT
CONTINUITY IN LINE WITH THE NATIONAL BLEND OF MODELS, BUT DID
ADJUST NBM CONVECTIVE RAINFALL FOCUS SOUTHWARD OVER THE SOUTHERN
PLAINS FRIDAY/SATURDAY MORE IN LINE WITH THE ECMWF/CMWF ENSEMBLE
MEAN GIVEN GROWING RETURN FLOW AND HEIGHT FALLS/UPPER JET SUPPORT.
..WEATHER/HAZARDS HIGHLIGHTS
A FRONTAL WAVE WILL LAY A FRONT ACROSS THE SOUTH NEAR THE GULF
COAST WEDNESDAY, PROVIDING THE FOCUS FOR ADDITIONAL AFTERNOON AND
EVENING SHOWERS AND THUNDERSTORMS. SOME OF THIS ACTIVITY MAY
CONTAIN HEAVY RAINFALL RATES GIVEN ADEQUATE MOISTURE AND
INSTABILITY, BUT ANY FLOODING CONCERNS SHOULD REMAIN LOCALIZED.
THUS, A NULL DAY 4/WEDNESDAY EXCESSIVE RAINFALL OUTLOOK (ERO) IS
MAINTAINED WITH THIS FORECAST UPDATE. THE AFOREMENTIONED FRONTAL
WAVE WILL TRACK OFF THE MID-ATLANTIC COAST WEDNESDAY INTO
THURSDAY, SPREADING MUCH NEEDED RAINFALL TO MUCH OF THE EASTERN
U.S. BY THE END OF THE WEEK, A GROWING SIGNAL FOR DEEPER COASTAL
LOW DEVELOPMENT AND ANOMALOUS LONG-FETCH GULF/ATLANTIC MOISTURE
WRAPPING INTO NEW ENGLAND WILL SUPPORT A HEAVY RAIN THREAT WITH THE
POTENTIAL FOR 1-3"+ OF RAINFALL. WHILE THE SIGNAL FOR HEAVY RAIN
IS NOTEWORTHY AND COULD LEAD TO RUNOFF OR LOCALIZED POOR DRAINAGE
FLOODING, RECENT MODERATE TO SEVERE DROUGHT CONDITIONS MAY RENDER
MOST OF THE RAIN MORE BENEFICIAL THAN HAZARDOUS. AS A RESULT, NO
DAY 5/THURSDAY ERO WAS HIGHLIGHTED FOR THE TIME BEING. THE COASTAL
LOW STALLS OUT LATER FRIDAY INTO THE WEEKEND, ALLOWING INTENSITY
TO WANE BUT KEEPING CONDITIONS COOL, WINDY, AND WET/UNSETTLED. A
LITTLE WRAPPING SNOW CAN'T BE RULED OUT EITHER ACROSS THE HIGHER
ELEVATIONS OF NORTHERN NEW ENGLAND OR THE INTERIOR NORTHEAST.
MEANWHILE, A SOUTHERN STREAM PACIFIC LOW WILL SLOWLY TRACK INLAND
ACROSS SOUTHERN CALIFORNIA, THE SOUTHWEST, AND THE FOUR CORNERS
STATES WEDNESDAY INTO THURSDAY, SPREADING LIGHT TO MODERATE LOW
ELEVATION RAIN AND HIGHER ELEVATION MOUNTAIN SNOW INTO THE REGION.
AS THIS FEATURE EJECTS EASTWARD INTO THE SOUTHERN PLAINS, ANOTHER
GROWING SIGNAL FOR SIGNIFICANT RAINFALL DEVELOPS AND
EXPANDS/STRENGTHENS OVER THE SOUTH-CENTRAL U.S. THURSDAY INTO
FRIDAY. ANOMALOUS GULF MOISTURE OVERRUNNING A LINGERING FRONTAL
BOUNDARY COMBINED WITH IMPRESSIVE DYNAMICS AND FORCING FROM A
STRONG UPPER JET WILL LEAD TO THE POTENTIAL FOR RAINFALL TOTALS OF
1-3"+ ACROSS THE HEART OF TEXAS. DESPITE QUESTIONS WITH RESPECT TO
THE QUALITY OF INSTABILITY (PARTICULARLY WITH NORTHWARD EXTENT) AND
THE ONGOING DROUGHT CONDITIONS OVER PARTS OF THE REGION, THE HEAVY
RAIN SIGNAL IS CONCERNING ENOUGH FOR A MARGINAL RISK ERO FOR
RUNOFF/ISOLATED FLOODING ISSUES DAY 5/THURSDAY. WAVES ALONG THE
FRONTAL ZONE WILL EXPAND THE RAINFALL FOOTPRINT EASTWARD OVER THE
MID-SOUTH AND SOUTHEAST FRIDAY INTO THE WEEKEND, WITH ADDITIONAL
RISKS OF HEAVY RAIN/RUNOFF ISSUES TO BE MONITORED.
MILLER/SCHICHTEL
ADDITIONAL 3-7 DAY HAZARD INFORMATION CAN BE FOUND ON THE WPC MEDIUM RANGE HAZARDS OUTLOOK CHART AT:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/THREATS/THREATS.PHP
WPC MEDIUM RANGE 500MB HEIGHTS, SURFACE SYSTEMS, WEATHER GRIDS, QUANTITATIVE PRECIPITATION FORECAST, EXCESSIVE RAINFALL OUTLOOK, WINTER WEATHER OUTLOOK PROBABILITIES, HEAT INDICES AND KEY MESSAGES ARE AT:
HTTPS://WWW.WPC.NCEP.NOAA.GOV/MEDR/5DAYFCST500_WBG.GIF
HTTPS://WWW.WPC.NCEP.NOAA.GOV/MEDR/5DAYFCST_WBG_CONUS.GIF
HTTPS://WWW.WPC.NCEP.NOAA.GOV/5KM_GRIDS/5KM_GRIDSBODY.HTML
HTTPS://WWW.WPC.NCEP.NOAA.GOV/QPF/DAY4-7.SHTML
HTTPS://WWW.WPC.NCEP.NOAA.GOV/#PAGE=ERO
HTTPS://WWW.WPC.NCEP.NOAA.GOV/WWD/PWPF_D47/PWPF_MEDR.PHP?DAY=4
HTTPS://WWW.WPC.NCEP.NOAA.GOV/HEAT_INDEX.SHTML
HTTPS://WWW.WPC.NCEP.NOAA.GOV/#PAGE=OVW
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